Power-to-X in Regional Energy Systems discusses the role of these technologies in achieving a carbon-neutral economy and the impact on the energy markets, with implications for electricity, gas, hydrogen, and ancillary services. It focuses on the challenges and benefits of implementing PtX technologies in regional-scale applications. Emphasizing the role of PtX technologies as enablers of sector coupling, the book provides a comprehensive understanding of how these technologies integrate and interact with the industry, transportation, and residential sectors. It describes the significance of PtX, optimal planning, and cost-effective operation of PtX technologies across different sectors and the impact of PtX devices on energy markets. The book considers investing in PtX technologies and contributing to the transition to a sustainable economy. The book will interest professionals and policymakers working in various energy sectors. Researchers and academics in electrical engineering, power systems, renewable energy, and energy economics will also find the content useful.